JPH0574718B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shaft sealing method for an air compressor.

[Prior art]

Figures 1 and 2 show an example of a conventional air compressor, in which low-pressure air 2 from an inlet 1 is compressed by multistage blades 3, and then discharged as high-pressure air 4 from an outlet 5. In order to perform thrust balance, the back surface 8 of the thrust balance piston 7 provided on the high pressure side of the blade shaft 6 is opened to the suction port 1 side via the thrust balance line A. Therefore, since the back surface 8 is opened to the suction port 1 (negative pressure) side, the lubricating oil in the discharge side bearing section 9 is transferred through the thrust balance line A because the pressure on the back surface 8 becomes negative pressure. It is discharged to the suction port 1 side. In order to prevent this, it is necessary to supply seal air 11 to the labyrinth seal chamber 10 provided between the back surface 8 and the discharge side bearing part 9, and also to
It is necessary to supply seal air 11 to the bearing seal chamber 13 of the bearing section 12 on the side to prevent lubricating oil from getting mixed into the low pressure air 2, and also to supply seal air 11 to the seal chamber 20 of the bearing section 9 on the discharge side. In some cases, lubricating oil is supplied to prevent lubricating oil from leaking out of the machine, and a seal air source B and seal piping C are provided for this purpose.

However, in the above conventional system, the air (at high temperature) on the back surface 8 of the thrust balance piston 7 is released to the suction port 1 side via the thrust balance line A, so the temperature of the low pressure air 2 is reduced. This causes the problem that more power than necessary is required for compression and that the specified capacity cannot be produced. Furthermore, since it is necessary to independently provide a seal air source B and a seal pipe C for supplying the seal air 11, the structure is complicated and expensive.

[Purpose of the invention]

An object of the present invention is to facilitate shaft sealing and prevent temperature rise of low-pressure air by utilizing the back pressure of the thrust balance piston for sealing.

[Structure of the invention]

The present invention involves releasing the back pressure in the thrust balance piston of an air compressor to the atmosphere while adjusting the pressure with an orifice, and guiding the adjusted back pressure to the suction port bearing seal chamber to perform shaft sealing. This is designed to solve the problems of preventing the temperature rise of low-pressure air and facilitating shaft sealing all at once.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

3 and 4 show an example of the present invention applied to FIGS. 1 and 2, and the same reference numerals as in FIGS. 1 and 2 indicate the same parts. As shown in the figure, the pressure at the back surface 8 of the thrust balance piston 7 is released to the atmosphere 16 through an exhaust pipe 14 and an orifice 15, and a seal pipe 17 is branched in the middle of the exhaust pipe 14 to connect the suction port to the atmosphere 16. It is connected to the suction port side bearing seal chamber 13 on the first side and seals against leakage of lubricating oil. Furthermore, because of the above, the pressure on the back surface 8 becomes positive, so the lubricating oil in the discharge side bearing section 9 does not leak to the back surface 8 side, and therefore the labyrinth seal chamber 10 on the thrust balance piston 7 side is used for sealing. No need to supply air. Further, if necessary, a seal pipe 18 may be provided in the bearing seal chamber 20 to supply sealing air, or the seal pipe 18 may be further provided with an orifice 19 or the like.

As mentioned above, the thrust balance piston 7
Since the pressure at the back side 8 of the inlet is adjusted through the orifice 15 and released to the atmosphere 16, unlike the conventional system in which the back pressure is released to the suction port 1 side, the temperature of the low-pressure air increases. This kind of thing can be completely prevented.

In addition, the adjusted pressure of the back surface 8 is used as sealing air to be guided to the bearing seal chamber 13 on the suction port side through the seal pipe 17, and to the labyrinth seal chamber 10 on the thrust balance piston 7 side. Since the pressure on the back surface 8 becomes positive pressure, it is possible to prevent lubricating oil from leaking into the machine from the discharge side bearing part 9, so there is no need to supply sealing air. The configuration can be significantly simplified. In addition,
In the above, the pressure on the back surface 8 is released to the atmosphere 16, but since the air that is released is the air leaking from the pressure side of the air compressor, no problem arises.

It should be noted that the present invention is not limited only to the above-mentioned embodiments, and various changes may be made without departing from the gist of the present invention.

〔Effect of the invention〕

As described above, according to the shaft sealing method for an air compressor of the present invention, the back pressure of the thrust balance piston is adjusted and used as sealing air for the shaft seal, so the pressure is lower than in the past. It is possible to balance the thrust without causing a rise in air temperature, and it also eliminates the need for a seal air source and simplifies the piping structure, making it possible to implement it at low cost, while increasing back pressure. By increasing the pressure, it is possible to achieve excellent effects such as making it unnecessary to supply sealing air to the seal portion on the thrust balance piston side.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of a conventional air compressor, Fig. 2 is an enlarged explanatory diagram showing a part of Fig. 1 in detail, and Fig. 3 is an embodiment of the present invention applied to Fig. 1. FIG. 4 is an enlarged explanatory diagram showing a part of FIG. 3 in detail. 1 is an inlet port, 3 is a blade, 5 is a discharge port, 6 is a blade shaft, 7 is a thrust balance piston, 8 is a back surface, 9 and 12 are bearing parts, 10 is a labyrinth seal chamber, 13 and 20 are bearing seal chambers, 14
is the exhaust pipe, 15 is the orifice, 16 is the atmosphere, 17
indicates sealed piping.

Claims (1)

[Claims] 1. The back pressure in the thrust balance piston of the air compressor is adjusted by an orifice and released to the atmosphere, and the adjusted back pressure is guided to the bearing seal chamber on the suction port side to perform shaft sealing. A shaft sealing method for an air compressor.